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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 343 records · Page 19
All sourcesNASA NTRSDOE OSTI
NASA NTRS1973

The radiometer transfer function for the AAFE composite two-frequency radiometer scatterometer

A model was developed for the switching radiometer utilizing a continuous method of calibration. Sources of system degradation were identified and include losses and voltage standing wave ratios in front of the receiver input. After computing the three modes of operation, expressions were developed for the normalized radiometer output, the minimum detectable signal (normalized RMS temperature fluctuation), sensitivity, and accuracy correction factors).

Moore, J. H.↗
NASA NTRS1976

The measurement of the winds near the ocean surface with a radiometer-scatterometer on Skylab

The author has identified the following significant results. There were a total of twenty-six passes in the ZLV mode that yielded useful data. Six were in the in-track noncontiguous mode; all others were in the cross-track noncontiguous mode. The wind speed and direction, as effectively determined in a neutral atmosphere at 19.5 m above the sea surface, were found for each cell scanned by S193. It is shown how the passive microwave measurements were used both to compute the attenuation of the radar beam and to determine those cells where the backscatter measurement was suspect. Given the direction of the wind from some independent source, with the typical accuracy of measurement by available meteorological methods, a backscatter measurement at a nadir angle of 50, 43, or 32 deg can be used to compute the speed of the wind averaged over the illuminated area.

Pierson, W. J.↗
NASA NTRS1976

Definition and fabrication of an airborne scatterometer radar signal processor

A hardware/software system which incorporates a microprocessor design and software for the calculation of normalized radar cross section in real time was developed. Interface is provided to decommutate the NASA ADAS data stream for aircraft parameters used in processing and to provide output in the form of strip chart and pcm compatible data recording.

Source record↗
NASA NTRS1978

SEASAT A satellite scatterometer

The analyses performed in the early period of the program which formed the basis of the sensor design is reviewed, along with the sensor design. The test program is outlined, listing all tests performed and the environmental exposure (simulated) for each, as applicable. Ground support equipment designed and built for assembly integration and field testing is described. The software developed during the program and the algorithms/flow diagrams which formed the bases for the software are summarized.

Bianchi, R.↗
NASA NTRS1980

Measurement of soil moisture trends with airborne scatterometers

The author has identified the following significant results. Cursory examination of the data indicates that the listed row tillage practices at 90 deg to the radar beam are approximately 12.5db higher than other comparable agricultural land. The Seasat radar data show evidence that the high return occurs only at a narrow range in look direction near the 90 deg. Such a high increase in return compared to a 15db range in film response would indicate that rows seen crosswise would saturate optically processed data. This response to row direction will have an adverse effect on monitoring agricultural lands with L band radar systems. Preliminary examination indicates that there is no sensitivity to soil moisture at the 5 deg look angle when using a like-polarized L band system. Some sensitivity was evident at a look angle of 20 deg and only a weak sensitivity was indicated at 40 deg look angle. At both 20 deg and 40 deg there is a significant response to soil moisture and none to row direction. Steep angles or the 5 deg look angle using cross polarized (HB) L band system appear insensitive to row direction and soil moisture.

Blanchard, B. J.↗
NASA NTRS1979

Continuation of measurement of hydrologic soil-cover complex with airborne scatterometers

The author has identified the following significant results. Analysis of radar scatterometry data obtained over five flight lines in Texas by NASA C-130 aircraft demonstrated that multivariant radar data can be used to distinguish difference in land use, and hence be an indicator of surface runoff characteristics. The capability of using microwave sensors to detect flood inundation of timbered land was also determined.

Blanchard, B. J.↗
NASA NTRS1981

Interactive processing of SEASAT scatterometer data

The Man-computer Interactive Data Access System (McIDAS), adapted for the interactive processing of satellite-derived temperature soundings and cloud-track winds for the FGGE Special Effort, was adapted for the processing and evaluation of SEASAT data. The implementation of the McIDAS SEASAT processing system required (1) extensive modifications to the data base structure to store and display SASS winds, as well as corroborative level II data, model first guess fields and level III analyses, and (2) the development of software to dealias and analyze SASS wind vectors interactively.

Atlas, R.↗
NASA NTRS1982

Measurement of soil moisture trends with airborne scatterometers

In an effort to investigate aircraft multisensor responses to soil moisture and vegetation in agricultural fields, an intensive ground sampling program was conducted in Guymon, Oklahoma and Dalhart, Texas in conjunction with aircraft data collected for visible/infrared and passive and active microwave systems. Field selections, sampling techniques, data processing, and the aircraft schedule are discussed for both sites. Field notes are included along with final (normalized and corrected) data sets.

Jones, C. L.↗